Toner refers to paint that is used for electrophotograph development, electrostatic printer and copier, and the like, and may be transferred and fixed on a transferred article to form desired pattern. Recently, as computer documentation becomes more common, there is rapidly increasing demand of image forming apparatus such as a printer, and thereby, toner consumption is also increasing.
A method for preparing toner includes a pulverization method and a polymerization method. According to the most widely known pulverization method, resin and pigment are introduced together through a melting-mixing process, melt-mixed or extruded, and then, pulverized/classified to prepare toner particles. However, since toner particles prepared by this process have non-uniform shape of wide particle diameter distribution, sharp edge, and the like, they have poor chargeability or flowability.
To overcome the above problem, a method of preparing spherical toner particles by polymerization has been suggested. As the method of preparing toner by polymerization, an emulsion polymerization/coagulation method and a suspension polymerization method are known. However, since the emulsion polymerization is difficult to control particle size distribution and has problem in reproducibility of toner quality, the suspension polymerization method is preferred.
However, magenta toner particles formed by suspension polymerization have wide particle size distribution and require a separation process, and a toner prepared using them has low transfer efficiency. For example, when polymerized toner is prepared using pigment having a structure of naphthol, carmine, rhodamine, azo, and the like, although colors required in the market may be satisfied, volume average particle diameter distribution is wide thus requiring a separation process, and transfer efficiency is low.
To keep pace with the future high speed, small size and light weight of printers and copiers, toner cartridge is also being miniaturized. Thus, for miniaturization of cartridge in high speed printers and copiers capable of printing a lot of copies, miniaturization of a drum part where toner waste is collected is required. Therefore, transfer efficiency that enables waste reduction is very important among toner qualities.